| Summary: | 碩士 === 逢甲大學 === 環境工程與科學所 === 96 === This study investigates using MSW incinerator fly ash co-sintered with water treatment plant (WTP) sludge for ceramic materials applications. The experiments were conducted at temperatures ranged from 1060 to 1100℃ and basicity ranged from 0.08 to 0.27, respectively. The experimental results revealed that the ceramic products sintered at 1060℃ were not in compliant with the criteria for application. The bending strengths of sintered products were approximately 29.57±7.76 kgf/cm2. However, in case of sintering temperature 1100℃, the water absorption and bending strength of sintered products were 0.84±0.17% and 185±22 kgf/cm2, respectively. The characteristics of sintered products all complied with the relevant ceramic materials criteria for construction work. According to the results of basicity effect on materials characteristics of products, the total porosity and water absorption of ceramic products decreased with basicity decreased, ranged from 60.89±0.25% to 1.54±1.18% and from 27.15±0.40% to 0.12±0.04%, respectively. However, the apparent density and bending strength of products increased with a decrease in basicity. Meanwhile, the major speciation of sintered products was anorthite (CaAl2Si2O8) that enhanced mechanical strength of ceramic products.
To assess the reaction rate of sintering, the activation energy of reaction was analyzed by dilatometer analysis. The experimental results indicated that the activation energy of sintering decreased from 423.44±280.85 kJ/mol to 140.44±24.73kJ/mol with basicity decreased from 0.27 to 0.08. Besides, the sintering rate of ceramic products increased from 0.04 %/min to 0.14 %/min with a decrease in basicity. In case of 100% WTP sludge, the densification of ceramic products occurred at 1015℃ and it could concluded that the WTP sludge addition will enhance the densification of ceramic products occurred.
The assessment for environmental safety of sintered products was conducted by the toxic characteristic leaching procedure (TCLP) concentration and acid neutralization capacity. The TCLP concentrations of Pb, Cr, Cd, Cu ,and Zn were all in compliant with Taiwan regulation thresholds. According to the results of residual rate of tested metals of ceramic products, the residual rate of Cu and Zn were 81.04% and 60.62%, respectively, and the residual rate increased with basicity decreased. That is, the tested metals, Cu and Zn, could be fixed in the matrix of sintered products. Meanwhile, the released amounts of Cr and Pb of ceramic products were below than the detection limit, and the released amounts of Cu and Zn were approximately 0.23 mg/meq.g and 0.57 mg/meq.g, respectively. In conclusion, the useful ceramic materials manufactured from 30% MSWI fly ash and 70% WTP sludge (basicity 0.19) and sintered at 1100℃.The results of this research also confirm the feasibility of co-sintering of WTP sludge and MSWI fly ash and promote the potential application in ceramic materials manufacturing.
Keyword: MSW incinerator fly ash；water treatment plant sludge；sintering rate；activation energy；residual rate
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